title: Diesel exhaust particle exposure increases severity of allergic asthma in young mice.
abstract: BACKGROUND
  Epidemiologic studies have reported an association between diesel exhaust particle (DEP) exposure, allergic sensitization, and childhood wheezing, although the mechanisms remain unclear. While DEP is known to augment allergic responses in adult animal models, its effects on sensitization and asthma severity in young animals is unknown.
  
  
  OBJECTIVE
  To examine the impact of different doses of DEP and allergen co-exposure on allergic sensitization and asthma characteristics in young mice, and whether Th17 as well as Th2 responses are induced.
  
  
  METHODS
  Lungs of 3-week-old wild-type Balb/c mice were exposed by pharyngeal aspiration nine times over 3 weeks to DEP at 1.2 or 6.0 mg/kg body weight, house dust mite (HDM) at 0.8, 1.2 or 6.0 mg/kg of DEP in combination with HDM, or the same volume (50 μL) of 0.9% sterile saline.
  
  
  RESULTS
  In young mice, exposure to 1.2 mg/kg of DEP caused no detectable lung inflammation, but 6.0 mg/kg of DEP induced neutrophilic influx. Compared to HDM or DEP alone, mice exposed to either dose of DEP together with HDM demonstrated increased allergen-specific IgE, lung inflammation, airway hyperreactivity, goblet cell metaplasia, Th2/Th17 cytokines, dendritic cells, activated T cells, effector T cells, and IL-17(pos) and IL-13(pos) /IL-17A(pos) T effector cells.
  
  
  CONCLUSIONS
  In young mice, co-exposure to DEP and HDM together exacerbated allergic sensitization and induced key characteristics of more severe asthma, including IL-17A, IL-17(pos) and IL-13(pos) /IL-17A(pos) T effector cells. While exposure to 1.2 mg/kg DEP alone caused no detectable changes, it did exacerbate allergic sensitization and asthma characteristics to a similar degree as a five-fold higher dose of DEP. This study demonstrates that exposure to DEP, even at a dose that alone causes no inflammation, exacerbates allergic asthma in young animals and suggests the importance of preventive measures to reduce the exposure of children to traffic related air pollution.
authors.affiliation: Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: T H
authors.initials: TH
authors.lastname: Acciani
authors.forename: E B
authors.initials: EB
authors.lastname: Brandt
authors.forename: G K
authors.initials: GK
authors.lastname: Khurana Hershey
authors.forename: T D
authors.initials: TD
authors.lastname: Le Cras
mesh_terms: D000367:Age Factors; D000393:Air Pollutants / Q000009:adverse effects; D000485:Allergens / Q000276:immunology; D000818:Animals; D001249:Asthma / Q000209:etiology* / Q000473:pathology; D016535:Bronchial Hyperreactivity / Q000209:etiology / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D004195:Disease Models, Animal; D020397:Goblet Cells / Q000473:pathology; D007073:Immunoglobulin E / Q000276:immunology; D008168:Lung / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008679:Metaplasia; D051379:Mice; D052638:Particulate Matter / Q000009:adverse effects* / Q000276:immunology; D012720:Severity of Illness Index; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D001335:Vehicle Emissions
chemical_list: D000393:Air Pollutants; D000485:Allergens; D016207:Cytokines; D052638:Particulate Matter; D001335:Vehicle Emissions; D007073:Immunoglobulin E
keywords: T cells; Th17; Th2; air pollution; allergen; asthma; atopy; dendritic cells; diesel exhaust particle; house dust mite